mirror_zfs/include/sys/dmu_recv.h
Brian Behlendorf caf9dd209f
Fix send/recv lost spill block
When receiving a DRR_OBJECT record the receive_object() function
needs to determine how to handle a spill block associated with the
object.  It may need to be removed or kept depending on how the
object was modified at the source.

This determination is currently accomplished using a heuristic which
takes in to account the DRR_OBJECT record and the existing object
properties.  This is a problem because there isn't quite enough
information available to do the right thing under all circumstances.
For example, when only the block size changes the spill block is
removed when it should be kept.

What's needed to resolve this is an additional flag in the DRR_OBJECT
which indicates if the object being received references a spill block.
The DRR_OBJECT_SPILL flag was added for this purpose.  When set then
the object references a spill block and it must be kept.  Either
it is update to date, or it will be replaced by a subsequent DRR_SPILL
record.  Conversely, if the object being received doesn't reference
a spill block then any existing spill block should always be removed.

Since previous versions of ZFS do not understand this new flag
additional DRR_SPILL records will be inserted in to the stream.
This has the advantage of being fully backward compatible.  Existing
ZFS systems receiving this stream will recreate the spill block if
it was incorrectly removed.  Updated ZFS versions will correctly
ignore the additional spill blocks which can be identified by
checking for the DRR_SPILL_UNMODIFIED flag.

The small downside to this approach is that is may increase the size
of the stream and of the received snapshot on previous versions of
ZFS.  Additionally, when receiving streams generated by previous
unpatched versions of ZFS spill blocks may still be lost.

OpenZFS-issue: https://www.illumos.org/issues/9952
FreeBSD-issue: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233277

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8668
2019-05-07 15:18:44 -07:00

72 lines
2.3 KiB
C

/*
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*
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*
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* If applicable, add the following below this CDDL HEADER, with the
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2018 by Delphix. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
*/
#ifndef _DMU_RECV_H
#define _DMU_RECV_H
#include <sys/inttypes.h>
#include <sys/dsl_bookmark.h>
#include <sys/dsl_dataset.h>
#include <sys/spa.h>
extern const char *recv_clone_name;
typedef struct dmu_recv_cookie {
struct dsl_dataset *drc_ds;
struct dmu_replay_record *drc_drr_begin;
struct drr_begin *drc_drrb;
const char *drc_tofs;
const char *drc_tosnap;
boolean_t drc_newfs;
boolean_t drc_byteswap;
boolean_t drc_force;
boolean_t drc_resumable;
boolean_t drc_raw;
boolean_t drc_clone;
boolean_t drc_spill;
struct avl_tree *drc_guid_to_ds_map;
nvlist_t *drc_keynvl;
zio_cksum_t drc_cksum;
uint64_t drc_fromsnapobj;
uint64_t drc_newsnapobj;
uint64_t drc_ivset_guid;
void *drc_owner;
cred_t *drc_cred;
} dmu_recv_cookie_t;
int dmu_recv_begin(char *tofs, char *tosnap,
struct dmu_replay_record *drr_begin, boolean_t force, boolean_t resumable,
nvlist_t *localprops, nvlist_t *hidden_args, char *origin,
dmu_recv_cookie_t *drc);
int dmu_recv_stream(dmu_recv_cookie_t *drc, struct vnode *vp, offset_t *voffp,
int cleanup_fd, uint64_t *action_handlep);
int dmu_recv_end(dmu_recv_cookie_t *drc, void *owner);
boolean_t dmu_objset_is_receiving(objset_t *os);
#endif /* _DMU_RECV_H */